.page-about {
  --about-gap: clamp(20px, 3vw, 40px);
  --about-tight: clamp(12px, 2vw, 20px);
  padding-bottom: clamp(64px, 8vw, 120px);
}

.page-about .breadcrumbs {
  margin: 24px 0 clamp(20px, 3vw, 34px);
}

/* ---------- Hero ---------- */
.page-about .aboutHero {
  padding-bottom: clamp(40px, 6vw, 72px);
}

.page-about .aboutHero__title {
  margin: 16px 0 0;
  font-size: clamp(32px, 6.2vw, 74px);
  line-height: 1.06;
  letter-spacing: -0.02em;
  font-weight: 300;
  max-width: 17ch;
}

.page-about .aboutHero__lead {
  margin: clamp(20px, 3vw, 30px) 0 0;
  max-width: var(--measure);
  font-size: 16px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .aboutHero__facts {
  list-style: none;
  margin: clamp(32px, 5vw, 52px) 0 0;
  padding: 1px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--grid-line);
  border: 1px solid var(--grid-line);
}

.page-about .aboutHero__facts li {
  background: var(--ink-green-900);
  padding: clamp(16px, 2.4vw, 24px) clamp(14px, 2vw, 22px);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .aboutHero__num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 3.6vw, 36px);
  font-weight: 600;
  line-height: 1;
  color: var(--lime-400);
}

.page-about .aboutHero__lbl {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist);
}

/* ---------- 时间线 ---------- */
.page-about .aboutTimeline {
  padding: clamp(40px, 6vw, 76px) 0 clamp(24px, 4vw, 48px);
}

.page-about .aboutTimeline--tail {
  padding-top: 0;
}

.page-about .aboutTimeline__head {
  margin-bottom: clamp(28px, 4vw, 44px);
}

.page-about .aboutTimeline__title {
  margin: 14px 0 0;
  font-size: clamp(24px, 4vw, 44px);
  font-weight: 300;
  line-height: 1.16;
  letter-spacing: -0.015em;
  max-width: 22ch;
}

.page-about .aboutTimeline__lead {
  margin: 18px 0 0;
  max-width: var(--measure);
  font-size: 16px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .aboutTimeline__figure {
  margin: 0 0 clamp(36px, 5vw, 60px);
}

/* ---------- 阶段索引 + 叙事 ---------- */
.page-about .timeline {
  display: grid;
  gap: clamp(24px, 4vw, 40px);
}

.page-about .timeline__index {
  border-top: 1px solid var(--grid-line);
  padding-top: 16px;
}

.page-about .timeline__indexList {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .timeline__indexList a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--grid-line);
  color: var(--mist);
  text-decoration: none;
  font-size: 12px;
  letter-spacing: 0.05em;
  transition: border-color 180ms var(--ease), color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .timeline__indexList a:hover,
.page-about .timeline__indexList a:focus-visible {
  border-color: var(--lime-400);
  color: var(--lime-400);
  background: rgba(199, 249, 74, 0.07);
}

.page-about .timeline__idx {
  font-family: var(--font-mono);
  color: var(--amber-500);
}

.page-about .timeline__body {
  display: grid;
  gap: clamp(24px, 4vw, 40px);
}

/* ---------- 单个阶段 ---------- */
.page-about .stage {
  position: relative;
  scroll-margin-top: 120px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-tight);
  padding: clamp(26px, 4vw, 44px) 0 clamp(32px, 5vw, 56px);
  border-top: 1px solid var(--grid-line);
}

.page-about .stage::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--lime-400);
  box-shadow: 0 0 0 3px rgba(199, 249, 74, 0.16);
}

.page-about .stage__meta {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.page-about .stage__year {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--amber-500);
}

.page-about .stage__title {
  margin: 0 0 14px;
  font-size: clamp(20px, 2.6vw, 28px);
  font-weight: 400;
  line-height: 1.3;
  letter-spacing: -0.01em;
  max-width: 24ch;
}

.page-about .stage__main p {
  margin: 0 0 14px;
  max-width: var(--measure);
  font-size: 16px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .stage__main p:last-child {
  margin-bottom: 0;
}

.page-about .stage__aside {
  display: flex;
}

.page-about .stage__stat {
  border-left: 1px solid var(--grid-line);
  padding: 4px 0 4px 14px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  cursor: default;
}

.page-about .stage__stat:focus-visible {
  outline: 1px solid var(--lime-400);
  outline-offset: 4px;
}

.page-about .stage__statNum {
  font-family: var(--font-mono);
  font-size: clamp(22px, 2.8vw, 30px);
  font-weight: 600;
  line-height: 1;
  color: var(--ice-blue);
}

.page-about .stage__statLbl {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--mist);
}

.page-about .stage__statTip {
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  font-size: 12px;
  line-height: 1.7;
  color: var(--mist);
  transition: max-height 220ms var(--ease), opacity 220ms var(--ease), margin-top 220ms var(--ease);
}

.page-about .stage__stat:hover .stage__statTip,
.page-about .stage__stat:focus .stage__statTip,
.page-about .stage__stat:focus-within .stage__statTip {
  max-height: 120px;
  opacity: 1;
  margin-top: 8px;
}

/* ---------- 分隔区 ---------- */
.page-about .aboutInterlude {
  padding: clamp(48px, 7vw, 96px) 0 clamp(32px, 5vw, 60px);
}

.page-about .aboutInterlude__figure {
  margin: 0;
}

.page-about .aboutInterlude__note {
  margin: 20px 0 0;
  max-width: var(--measure);
  font-size: 15px;
  line-height: 1.8;
  color: var(--amber-500);
  padding-left: 14px;
  border-left: 2px solid var(--amber-500);
}

/* ---------- 频道 ---------- */
.page-about .aboutChannels {
  padding: clamp(48px, 7vw, 96px) 0;
  background: linear-gradient(180deg, rgba(20, 23, 26, 0) 0%, rgba(20, 23, 26, 0.75) 22%, rgba(20, 23, 26, 0.75) 78%, rgba(20, 23, 26, 0) 100%);
}

.page-about .aboutChannels__head {
  margin-bottom: clamp(28px, 4vw, 44px);
}

.page-about .aboutChannels__title {
  margin: 12px 0 0;
  font-size: clamp(24px, 3.6vw, 40px);
  font-weight: 300;
  line-height: 1.18;
  letter-spacing: -0.015em;
}

.page-about .channelList {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--grid-line);
  border: 1px solid var(--grid-line);
}

.page-about .channelList__item {
  background: var(--ink-green-900);
  padding: clamp(22px, 3.2vw, 34px) clamp(18px, 2.6vw, 28px);
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: background-color 200ms var(--ease);
}

.page-about .channelList__item:hover {
  background: var(--charcoal-800);
}

.page-about .channelList__num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--amber-500);
}

.page-about .channelList__name {
  margin: 0;
  font-size: clamp(18px, 2.2vw, 22px);
  font-weight: 400;
  letter-spacing: -0.01em;
}

.page-about .channelList__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .channelList__link {
  margin-top: 4px;
  align-self: flex-start;
  font-size: 13px;
  letter-spacing: 0.05em;
  color: var(--lime-400);
  text-decoration: none;
  border-bottom: 1px solid rgba(199, 249, 74, 0.35);
  padding-bottom: 2px;
  transition: border-color 180ms var(--ease), color 180ms var(--ease);
}

.page-about .channelList__link:hover,
.page-about .channelList__link:focus-visible {
  border-bottom-color: var(--lime-400);
  color: var(--paper);
}

/* ---------- 团队 ---------- */
.page-about .aboutTeam {
  padding: clamp(48px, 7vw, 96px) 0;
}

.page-about .aboutTeam__grid {
  display: grid;
  gap: clamp(28px, 4vw, 48px);
}

.page-about .aboutTeam__title {
  margin: 12px 0 0;
  font-size: clamp(24px, 3.4vw, 38px);
  font-weight: 300;
  line-height: 1.2;
  letter-spacing: -0.015em;
  max-width: 20ch;
}

.page-about .aboutTeam__lead {
  margin: 18px 0 0;
  max-width: var(--measure);
  font-size: 16px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .flowList {
  list-style: none;
  margin: clamp(26px, 4vw, 38px) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--grid-line);
  border-top: 1px solid var(--grid-line);
  border-bottom: 1px solid var(--grid-line);
}

.page-about .flowList__item {
  background: var(--ink-green-900);
  padding: 18px 0;
  display: grid;
  gap: 8px;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .flowList__stage {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.16em;
  color: var(--lime-400);
}

.page-about .flowList__item p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist);
  max-width: var(--measure);
}

.page-about .aboutTeam__stat {
  margin: clamp(24px, 3.6vw, 34px) 0 0;
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex-wrap: wrap;
}

.page-about .aboutTeam__statNum {
  font-family: var(--font-mono);
  font-size: clamp(30px, 4.4vw, 46px);
  font-weight: 600;
  line-height: 1;
  color: var(--amber-500);
}

.page-about .aboutTeam__statLbl {
  font-size: 13px;
  letter-spacing: 0.05em;
  color: var(--mist);
}

.page-about .aboutTeam__figure {
  margin: 0;
}

/* ---------- 版本迭代 ---------- */
.page-about .aboutVersions {
  padding: clamp(48px, 7vw, 96px) 0;
}

.page-about .aboutVersions__head {
  margin-bottom: clamp(28px, 4vw, 44px);
}

.page-about .aboutVersions__title {
  margin: 12px 0 0;
  font-size: clamp(22px, 3.2vw, 36px);
  font-weight: 300;
  line-height: 1.22;
  letter-spacing: -0.015em;
  max-width: 26ch;
}

.page-about .aboutVersions__lead {
  margin: 16px 0 0;
  max-width: var(--measure);
  font-size: 15px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .versionTrack {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
  position: relative;
}

.page-about .versionTrack__item {
  position: relative;
  padding: 0 0 clamp(28px, 4vw, 44px) 28px;
  border-left: 1px solid var(--grid-line);
}

.page-about .versionTrack__item:last-child {
  padding-bottom: 0;
  border-left-color: transparent;
}

.page-about .versionTrack__item:last-child::before {
  content: "";
  position: absolute;
  top: 12px;
  left: -1px;
  width: 1px;
  height: calc(100% - 12px);
  background: linear-gradient(180deg, var(--violet-500) 0%, rgba(108, 92, 231, 0) 100%);
}

.page-about .versionTrack__dot {
  position: absolute;
  top: 6px;
  left: -5px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--violet-500);
}

.page-about .versionTrack__dot--current {
  background: var(--lime-400);
  animation: aboutPulse 2.4s var(--ease) infinite;
}

@keyframes aboutPulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(199, 249, 74, 0.45); }
  50% { box-shadow: 0 0 0 8px rgba(199, 249, 74, 0); }
}

.page-about .versionTrack__label {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--mist);
}

.page-about .versionTrack__name {
  margin: 8px 0 10px;
  font-family: var(--font-mono);
  font-size: clamp(20px, 2.6vw, 26px);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--paper);
}

.page-about .versionTrack__item p {
  margin: 0;
  max-width: var(--measure);
  font-size: 15px;
  line-height: 1.8;
  color: var(--mist);
}

/* ---------- 合作 ---------- */
.page-about .aboutCollab {
  padding: clamp(48px, 7vw, 96px) 0 0;
  border-top: 1px solid var(--grid-line);
  margin-top: clamp(16px, 3vw, 32px);
}

.page-about .aboutCollab__head {
  margin-bottom: clamp(26px, 4vw, 40px);
}

.page-about .aboutCollab__title {
  margin: 12px 0 0;
  font-size: clamp(24px, 3.4vw, 38px);
  font-weight: 300;
  line-height: 1.2;
  letter-spacing: -0.015em;
  max-width: 22ch;
}

.page-about .aboutCollab__lead {
  margin: 16px 0 0;
  max-width: var(--measure);
  font-size: 15px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .collabPanels {
  display: grid;
  gap: 1px;
  background: var(--grid-line);
  border-top: 1px solid var(--grid-line);
  border-bottom: 1px solid var(--grid-line);
}

.page-about .collabPanel {
  background: var(--ink-green-900);
}

.page-about .collabPanel__summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: clamp(16px, 2.4vw, 22px) 0;
  font-size: clamp(15px, 1.8vw, 17px);
  color: var(--paper);
  transition: color 180ms var(--ease);
}

.page-about .collabPanel__summary::-webkit-details-marker {
  display: none;
}

.page-about .collabPanel__summary:hover,
.page-about .collabPanel__summary:focus-visible {
  color: var(--lime-400);
  outline: none;
}

.page-about .collabPanel__summary:focus-visible {
  box-shadow: inset 0 0 0 1px var(--lime-400);
}

.page-about .collabPanel__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--amber-500);
  flex: 0 0 auto;
}

.page-about .collabPanel__label {
  flex: 1 1 auto;
}

.page-about .collabPanel__mark {
  flex: 0 0 auto;
  width: 12px;
  height: 12px;
  position: relative;
}

.page-about .collabPanel__mark::before,
.page-about .collabPanel__mark::after {
  content: "";
  position: absolute;
  background: currentColor;
  transition: transform 200ms var(--ease);
}

.page-about .collabPanel__mark::before {
  top: 50%;
  left: 0;
  width: 12px;
  height: 1px;
  transform: translateY(-50%);
}

.page-about .collabPanel__mark::after {
  left: 50%;
  top: 0;
  width: 1px;
  height: 12px;
  transform: translateX(-50%);
}

.page-about .collabPanel[open] .collabPanel__mark::after {
  transform: translateX(-50%) scaleY(0);
}

.page-about .collabPanel__body {
  padding: 0 0 clamp(20px, 3vw, 28px) 30px;
}

.page-about .collabPanel__body p {
  margin: 0 0 12px;
  max-width: var(--measure);
  font-size: 14px;
  line-height: 1.85;
  color: var(--mist);
}

.page-about .collabPanel__body p:last-child {
  margin-bottom: 0;
}

.page-about .aboutCollab__actions {
  margin-top: clamp(28px, 4vw, 44px);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .aboutHero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .channelList {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .flowList__item {
    grid-template-columns: 120px minmax(0, 1fr);
    align-items: start;
    gap: 20px;
  }
}

@media (min-width: 960px) {
  .page-about .timeline {
    grid-template-columns: 190px minmax(0, 1fr);
    column-gap: clamp(36px, 5vw, 64px);
    align-items: start;
  }

  .page-about .timeline__index {
    position: sticky;
    top: 104px;
  }

  .page-about .timeline__indexList {
    flex-direction: column;
    flex-wrap: nowrap;
  }

  .page-about .timeline__indexList a {
    width: 100%;
  }

  .page-about .stage {
    grid-template-columns: minmax(0, 1fr) 190px;
    column-gap: clamp(28px, 4vw, 48px);
    row-gap: 18px;
  }

  .page-about .stage__meta {
    grid-column: 1 / -1;
  }

  .page-about .stage__main {
    grid-column: 1;
  }

  .page-about .stage__aside {
    grid-column: 2;
    align-items: flex-start;
  }

  .page-about .aboutTeam__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.85fr);
    column-gap: clamp(36px, 5vw, 64px);
    align-items: start;
  }

  .page-about .aboutTeam__figure {
    position: sticky;
    top: 104px;
  }

  .page-about .versionTrack {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0;
    border-top: 1px solid var(--grid-line);
  }

  .page-about .versionTrack__item {
    padding: clamp(26px, 3.4vw, 38px) clamp(20px, 2.6vw, 30px) clamp(26px, 3.4vw, 38px) 0;
    border-left: none;
    border-right: 1px solid var(--grid-line);
  }

  .page-about .versionTrack__item:last-child {
    border-right-color: transparent;
    padding-right: 0;
  }

  .page-about .versionTrack__item:last-child::before {
    display: none;
  }

  .page-about .versionTrack__dot {
    top: -5px;
    left: 0;
  }
}

@media (min-width: 1180px) {
  .page-about .channelList {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .aboutHero__title {
    max-width: 19ch;
  }
}

@media (hover: none) {
  .page-about .stage__statTip {
    max-height: 120px;
    opacity: 1;
    margin-top: 8px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .versionTrack__dot--current {
    animation: none;
  }

  .page-about .stage__statTip,
  .page-about .channelList__item,
  .page-about .timeline__indexList a,
  .page-about .collabPanel__summary,
  .page-about .collabPanel__mark::before,
  .page-about .collabPanel__mark::after {
    transition: none;
  }
}